Abstraction of Nitrogen from the Aimosphere. 91 
the fiery globe, in its passage to the state in which we now 
find it. 
As yet, I am not prepared to say that the primitive rocks are 
of the origin imputed to them by the Plutonians, nor am I dis- 
posed to assent to the opinions of the Neptunians ; fortoo few 
facts are known to enable me to coincide with either of those 
schools in their sweeping conclusions. If the igneous origin 
of the primitive class of rocks were fully adequate to explain 
the facts in question, still it is subject to the objection of being 
founded too much upon analogy, and ought not to be put in 
competition with the veiw or theory which explains the facts, 
by causes deduced from positive knowledge. 
ith respect to the position of the abstraction of nitrogen 
from the atmosphere, it is, as before mentioned, the deduction 
from the result of our experimental knowledge ; for all the 
known minerals which preceded organization, have 
analysed, with the exception of one of them, (macle or chias- 
tolite) and nothing is so rare as the discovery of a new mine- 
ral, which at the same time is an abundant one. The im- 
portance of the position will be better appreciated, when ge-— 
ology shall have made such advances, as that each mass of 
tive quantities cf nitrogen—for then the result, in a measure, 
becomes the subject of calculation. 
Facts which show an abstraction of oxygen from the atmos- 
: phere, Se. 
With a few exceptions, which, at most, for quantity, are— 
merely fractional, all the mineral iron which is found contem- 
raneously with the rocks of the primitive class, is in the 
state of the black oxide; the ferroso-ferricum of Berzelius. 
The iron existing in combinations, or with carbonic, or any 
other acid, is in the state of the protoxide. Iron has not the 
property of decomposing water, unless ata heat. It can 
acquire oxygen only by means of moisture and atmospheric 
air. 
Pyrites, or sulphuret of iron, is extremely abundant in the 
primitive class, the debris of whose rocks have given rise to 
the whole of the materials of the mechanical rocks. Pyrites 
cannot decompose water ; like iron, it requires the agency of 
